Deep borehole disposal suitable for ERDO countries, study shows

14 December 2021

Deep borehole disposal is a viable, cost-effective solution for all of the intermediate and high-level long-lived radioactive waste (ILW/HLW) that is being temporarily stored by five European countries, according to a feasibility study by Deep Isolation. The study was commissioned by Norwegian Nuclear Decommissioning (NND) on behalf of the European Repository Development Organisation (ERDO), a multinational group established in 2021 to address the challenges of safely managing long-lived radioactive wastes either separately or in one combined mined repository.

(Image: Deep Isolation)

The report - published today by NND - presents an initial high-level assessment of the viability and costs of using Deep Isolation's deep borehole technology to dispose of radioactive waste from Croatia, Denmark, the Netherlands, Norway and Slovenia.

During 2021, NND has been leading a project within ERDO to study the suitability of deep borehole disposal as an alternative and lower-cost solution for elements of the waste inventories of the participating countries. Deep Isolation's study expands upon that research - presented to the International Atomic Energy Agency in November - which concluded that deep borehole disposal is "a technically feasible concept that adds to the range of technologies available for waste management organisations," offering "lower fixed costs and greater adaptability to small inventories."

The new study shows all of the collective inventory of heat-generating HLW from across the countries is technically and commercially feasible for deep borehole disposal.

"We estimate that just over 1% by volume [of the radioactive waste inventory] is suitable for borehole disposal," the study says. "This represents 100% of the heat-generating waste across the ERDO inventories. This means that the ERDO countries will still require one or more mined repositories to manage bulky ILW and non-heat-generating HLW that is unsuitable for borehole disposal. But by managing the heat-generating HLW at lower cost and at far greater depth in boreholes, the ERDO countries can see significant overall cost savings."

Deep Isolation estimates that a deep borehole repository would cost one-third to one-half of the cost of a traditional mined repository.

"Preliminary estimates, based on a high-level generic design for an integrated multi-national repository using horizontal boreholes, suggest that delivery of such a repository would cost between EUR418 million (USD472 million) and EUR560 million (USD633 million)," the report says. "On top of this, we estimate that the costs of regulatory compliance (including site characterisation, licensing and post-closure monitoring) might cost a further EUR124 million - although these estimates are considerably more uncertain. This total cost range of EUR542-684 million represents a saving of half to two-thirds of the likely cost of disposal in a mined deep geological repository, based on ERDO's earlier assessment of such costs."

The study makes recommendations for next steps, focused on a full-scale demonstrator facility that will support both elements of the dual-track approach - "actions that will be beneficial for all ERDO members, regardless of whether future decisions are to invest in an integrated multinational repository or individual national repositories."

Berkeley, California-based Deep Isolation's solution for the management of used nuclear fuel and high-level radioactive waste involves emplacing it in corrosion-resistant canisters placed in deep horizontal drillholes. The technology uses existing directional drilling technology. The waste can be retrieved during a determined timeframe or permanently secured. In 2019, Deep Isolation publicly demonstrated its concept when it successfully placed and then retrieved a prototype nuclear waste canister hundreds of metres underground via a borehole.

"The nuclear industry has long suffered from a lack of safe, affordable nuclear waste disposal solutions," said Deep Isolation CEO Liz Muller. "I commend the ERDO countries for exploring an option that leverages well-established directional drilling technologies to offer a more viable way forward. This is important not just for clearing up the legacy of nuclear waste being stored in temporary facilities worldwide but also for our global low-carbon future. Governments, as well as the public, increasingly recognise that safely isolating nuclear waste in permanent disposal is a prerequisite for new nuclear power, including advanced reactors."

In August, Deep Isolation was awarded a contract to conduct a borehole feasibility study for ARAO, Slovenia's radioactive waste management organisation. The study will examine whether a deep borehole repository could dispose of used fuel from Slovenia's TRIGA II research reactor at the Josef Stefan Institute in Ljubljana.

The company has completed other deep borehole disposal feasibility studies for advanced nuclear projects, including for the USA's Electric Power Research Institute and Estonia's Fermi Energia.

Researched and written by World Nuclear News